Recently, makers of photographic material have made efforts for reducing the amount of waste liquid formed in a photographic processing to a limit relating to a tendency of environment protection.
On the other hand, C-41RA Processing of Eastman Kodak Co., Ltd., which is a processing most widely used in-shop laboratories or mini-labo's, is composed of 4 steps, and the replenishing amounts per roll of 135 size, 24 exp. film are 23 ml for color developing step, 5 ml for bleaching step, 33 ml for fixing step and 40 ml for stabilizing step, respectively. The replenishing amount for the stabilizing solution is largest in these steps. Therefore, reducing in the replenishing amount of the stabilizing solution has been demanded.
However, when the replenishing amount of the stabilizing solution is simply reduced, a fixing agent such as thiosulfate, a component of a fixing solution, is accumulated in the stabilizing solution. The fixing agent is carried into the stabilizing solution from the previous fixing bath by a light-sensitive material processed on which the fixing agent is adhered. The accumulated fixing agent causes formation of a stain on the back surface of the light-sensitive material. The satin appears on a printed picture from the light-sensitive material and causes a serious defect destroying the commercial value of the print. Further, the renewing ratio of the stabilizing solution is lowered by the reduction of the replenishing amount, which causes an extension of time for oxidation of the stabilizing solution by air. As a result of that, a problem of formation of defects caused by sulfurization is apt to raise. Further, formaldehyde is usually contained in the stabilizing solution for preventing stain formation in a unexposed area of the processed light sensitive material during storage and discoloration of color image by blocking the reactive site of a unreacted magenta coupler remained in the light-sensitive material. The formaldehyde reacts and forms an adduct with sulfite, which is carried over from the fixing solution accompanied with the thiosulfate to the stabilizing solution. As a result of that, the effect of formaldehyde improving the stability of dye is lost and a serious problem of acceleration of sulfurizaton in the stabilizing solution is raised.
Recently, solidifying a processing composition for a silver halide light-sensitive material is tried from the view point of reducing environment pollution and improving working load for preparating a processing solution. For instance, Japanese Patent Publication Open to Public Inspection (JP O.P.I.) Nos. 5-119454/1993, 5-165174/1993 and 5-232656/1993 each describe a technology in which a solid processing composition containing thiosulfate is directly supplied into a solution having a fixing ability.
It would be unquestionable that reducing the use of plastic bottles for bottling a replenisher solution kit and lowering working load at the time of preparation of a replenisher solution can be attained by applying the technology disclosed in the above publications. However, it has been found that the problems mentioned below cannot be solved by the above technology only.
In the above-mentioned patent publications, a fixing time of 90 seconds for color negative film is disclosed as an embodiment of the technology. Generally, it is necessary to increase the concentration of thiosulfate in a processing solution to a certain level for attaining such rapidness of the processing. In the case in which thiosulfate concentration is made higher, it is apt to occur a problem, when daily cleaning of transferring rollers arranged between the first and the second fixing tank or a fixing tank and next tank such as a stabilizing tank or a washing tank is failed, that a hydrophobic decomposition substance of thiosulfate is formed by drying and air-oxidizing of drops of the processing solution adhered on the rollers by a light-sensitive material processed. The hydrophobic substance is tightly fixed on the surface of the rollers by hydrophilic bonding. The hydrophobic substance tightly adhered on the surfaces of the rollers may causes an irrevocable defect such as scratches on the light-sensitive material.
Further, it has been found, in the relation between concentration of thiosulfate and fixing property, that although the fixing property is raised with increasing the thiosulfate concentration until a certain value, the fixing property is lowered in reverse when the concentration exceeds the certain value. The thiosulfate concentration for enabling the above-mentioned rapid processing corresponds to the above critical concentration. Accordingly, when the amount of light-sensitive material to be processed per day is small, the thiosulfate concentration in the processing solution is apt to raised by evaporation of the solution. The raising in the thiosulfate concentration causes a problem that the fixing property of the solution is degraded. Further, crystals of thiosulfate are precipitated and grown in the processing solution when such the concentrated processing solution as described above is stood under a low temperature condition such as in a closing term in winter. The precipitation of thiosulfate causes blocking of circulation of the processing solution and degrades the property of the processing solution due to lowering the effective amount of thiosulfate in the processing solution.
On the other hand, in a case that a solid processing composition is stored for a prolonged period on the deck of a ship when the composition is transported by a ship, a yellow water-insoluble sulfurous substance is formed in a thiosulfate-containing solid composition for fixer or bleach-fixer during the storage under a such high temperature condition. The insoluble sulfurous substance adheres to a filter stalled in the fixing tank or bleach-fixing tank of processor and causes blocking of the filter. As a result of that, photographic properties of the processing solution are degraded due to in sufficient circulation of the processing solution. Further, it has been found that the precipitated sulfurous substance adheres on the surface of the processed light-sensitive material and considerably spoils the commercial value of the processed light-sensitive material.
In case of the solid composition is in a form of granule or tablet, the formation of sulfurous substance by decomposition of thiosulfate causes lowering the combining force between components of the composition around the sulfrous substance in the granule or the tablet. As a result of this, the solid composition is easily powdered by vibration or friction.
A solution for processing a silver halide photographic light-sensitive material having a fixing ability such as a fixier or a bleach-fixer contains compound which is capable of forming a water-soluble complex salt by reaction with silver halide for example, a thiosulfate such as potassium thiosulfate, sodium thiosulfate or ammonium thiosulfate, a thiocyanate such as potassium thiocyanate, sodium thiocyanate or ammonium thiocyanate, thiourea or a thioether is usually contained as a fixing agent. Among them, thiosulfate particularly ammonium thiosulfate has been frequently used by reason of that the compound is superior in the processing property, stability and solubility thereof.
However, a strong odor of evaporated ammonia is generated when ammonium ions are contained in a processing solution. It has been tried, therefore, to reduce the using amount of ammonium salt for improvement of working environment.
However, the solubility of potassium thiosulfate or sodium thiosulfate is lower than that of ammonium thiosulfate. Accordingly, the fixing agent is easily precipitated in a concentrated solution at low temperature when these thiosulfates are used instead of ammonium salt. The concentration of the solution is particularly occurred in a mini-labo when the amount of light-sensitive material to be processed is small. Further, in a system with a small amount of replenishing, it is required to increase the concentration of thiosulfate to compensate degradation in processing ability and stability of the processing solution. It has been found that the increasing in the thiosulfate concentration causes adhering sulfur on transferring rollers exposed to air, particularly on rollers for transferring provided at a position between a processing tank and the next processing tank (inter-tank rollers).